BLE scatternet system and method

ABSTRACT

A BLE network includes a first piconet (A) including a first master scanner (3-1) and a first group of low-power slave/advertisers (5-1,2 . . . 5) for transmitting wireless advertisements. Circuitry (3,55) in the first master/scanner wirelessly scans to detect an advertisement (58,62) transmitted by a first slave/advertiser (5-1) of the first group and transmits a connection request (58,62) in response to the detecting, and transmits a schedule (60) for subsequent advertisements after an initial advertisement by the first slave/advertiser. Circuitry (5,39) in the first slave/advertiser transmits the initial advertisement (42), receives an acceptance a resulting connection request, establishes association (44) with the first master scanner, and then causes the first slave/advertiser to go to sleep, to wake up and transmit subsequent advertisements according to the schedule (50) and accept resulting connection requests, and transmits available data to the first master/scanner, and goes back to sleep.

CROSS REFERENCE TO RELATED APPLICATION

This continuation application claims priority to U.S. patent applicationSer. No. 13/958,271, filed Aug. 2, 2013, which application claimspriority to and the benefit of Provisional Application Ser. No.61/828,282, filed May 29, 2013, both of which applications areincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to low energy BLE (Bluetooth LowEnergy) networks, and more particularly to low power/low energymechanisms and methods of establishing wireless connection between“nodes” of a scatternet or sensor network.

Those skilled in the art know that “Bluetooth” is a registeredbrand/trademark/certification mark for various wireless communicationstandards referred to herein as Bluetooth standards. The variousBluetooth standards have been developed and promulgated by the BluetoothSpecial Interest Group known as “Bluetooth SIG”. The variousbrands/trademarks/certification marks are owned and licensed to varioususers by Bluetooth SIG., Inc. for use on and in conjunction with variouscommunication devices. Up-to-date Bluetooth guidelines can be obtainedfrom the Bluetooth SIG, Inc. website “https//www.bluetooth.org/en-us”.Proper authorized use of the Bluetooth brands/trademark/certificationmarks is enforced by Bluetooth SIG, Inc., in order to ensure that thestandards are properly adhered to in accordance with the Bluetoothlicensing terms and guidelines.

The Bluetooth Low Energy (BLE) brand/standard/certification mark is nowcalled “Bluetooth Smart”. The standard called “Bluetooth 4.0”incorporates the BLE or Bluetooth Smart standard. The term “classicBluetooth” is used herein to refer to all versions of the Bluetoothstandards prior to Bluetooth 4.0. All of the Bluetooth standards aredeveloped by building certification standards/programs around certainparts of the IEEE 802.15.x family of specifications.

A “piconet” is basically a collection of slave/advertisers that arescanned by a master/scanner that could wirelessly connect to anotherpiconet. A “scatternet” is a type of ad-hoc computer network consistingof two or more piconets. The terms “scatternet and “piconet aretypically applied to Bluetooth wireless technology. Bluetooth Low Energy(BLE) is a feature of Bluetooth 4.0 wireless radio technology aimedprincipally at low-power and low-latency applications for wirelessdevices with a short range, up to approximately 160 feet, andfacilitates a wide range of applications.

“Prior Art” FIG. 1 shows a conventional BLE scatternet including apiconet A and a piconet B each including a “master” or “master/scanner”device capable of wireless communication with a number of nearby “slave”or “slave/advertiser” devices. Bluetooth low energy (BLE) has the lowestpower standard, and using BLE for the advertising of slave devices in apiconet provides the lowest known power consuming mechanism within theBLE standard. If it is desired to have the lowest power radio standardpresently available, BLE is considered to be the starting point.

In piconet A, master/scanner 3-1 is capable of wireless communicationwith/advertisers 5-1, 5-2, 5-3, 5-4, and 5-5 through wireless links 2-1,2-2, 2-3, 2-4, and 2-5, respectively. Similarly, in piconet B,master/scanner 10-2 is capable of wireless communicationwith/advertisers 5-6 and 5-7 through wireless links 2-6 and 2-7,respectively. Slave/advertiser 5-5 in piconet A also communicates withmaster 10-2 in piconet B through wireless link 7. In piconet A,master/scanner 3-1 can synchronize with any of the slave/advertisers inpiconet A, for example as represented by reference numeral 15, toestablish wireless link 2-1. After synchronization, master/scanner 3-1then may perform two-way wireless data communication with theslave/advertiser, for example as represented by reference numeral 17.The BLE scatternet shown Prior Art FIG. 1 could include many morepiconets that communicate with each other in essentially the mannerdescribed above. A shortcoming of the prior art shown in FIG. 1 is thatit fails to accommodate piconet slave/advertiser devices which mustoperate with very little power/energy because of the requirements of theBLE standards.

If achieving very low power consumption is not a concern, so-calledZigBee technology with its existing standard can be used. The BLEstandard is part of the Bluetooth 4.0 standard and is interoperable withmost mobile phones. ZigBee is a protocol that combines with the MAC(Media Access Control) protocol established by IEEE 802.15.4. It hasmultiple operational modes. It has been shown that advertisement is thelowest energy technique for wireless communication between “nodes” ofscatternets. However, the ZigBee standard is not operable in mobilephones. As far as the BLE standard is concerned, there is a “singlemode”, which is just the relatively new Bluetooth low energy mode ofoperation, and there also exists a “dual mode”, which supports “classic”Bluetooth standard operation as well as operation in accordance with theBLE low energy standard. Modern smart phones usually support both inorder to be able to wirelessly connect in both modes with older smartphones and new very low energy Bluetooth phones and devices,respectively.

The Bluetooth standard specifies standard connection time intervals thatare established at the beginning of the time interval during whichslave/advertiser devices connected in a piconet are allowed towirelessly communicate with other devices, but the communicationconnection intervals typically are limited to approximately fourseconds. Because of drift in the synchronization of internalcrystal-generated clock signals in the slave/advertiser devices in apiconet, is necessary for every slave/advertiser device in the piconetto “wake up” into a high power consumption condition approximately everyfour seconds. Such high power consumption is unacceptable in someapplications. If all the slave/advertisers need to be very low energydevices, then slave/advertisers would not ordinarily be used toaggregate data generated by the slave/advertiser devices in a piconetduring their allowed advertising time intervals and then wirelesslyconnect to the master/scanner of a different piconet, as shown by link 7in the prior art system shown in FIG. 1.

Thus, there is an unmet need for an economical, low-power/low-energytechnique for automatically establishing wireless connections within ascatternet.

There also is an unmet need for an improved economical,low-power/low-energy technique for utilizing standardized BLE mechanismsin a scatternet.

There also is an unmet need for a more power-efficient way ofpropagating information through a series of BLE nodes in a quasi-staticnetwork.

There also is an unmet need for an improved, power-efficient way ofsynchronizing a master/scanner with a plurality of slave/advertisers ina piconet.

There also is an unmet need for an improved, power-efficient way ofsynchronizing a master/scanner in one piconet with a master/scanner inanother piconet.

There also is an unmet need for a low-power/low-energy way of avoidingthe need for every slave/advertiser in a piconet to periodically wake upirrespective of whether the slave/advertiser needs to transmit data.

There also is an unmet need for a low-power/low-energy way ofpropagating messages between BLE-enabled mobile wireless devices andsensors without requiring hardware changes or firmware changes to theBLE-enabled devices.

There also is an unmet need for a low-power/low-energy way ofpropagating messages between BLE-enabled mobile wireless devices andsensors while efficiently avoiding the effects of drift between internalclock signals in various slave/advertiser devices and master/scannerdevices.

SUMMARY OF THE INVENTION

Is an object of the invention to provide an economical,low-power/low-energy technique for automatically establishing wirelessconnections within a scatternet.

It is another object of the invention to provide an improved economical,low-power/low-energy technique for utilizing standardized BLE mechanismsin a scatternet.

It is another object of the invention to provide a more power-efficientway of propagating information through a series of BLE nodes in aquasi-static network.

It is another object of the invention to provide an improved,power-efficient way of synchronizing a master/scanner with a pluralityof slave/advertisers in a piconet.

It is another object of the invention to provide an improved,power-efficient way of synchronizing a master/scanner in one piconetwith a master/scanner in another piconet.

It is another object of the invention to provide a low-power/low-energyway of avoiding the need for every slave/advertiser in a piconet toperiodically wake up irrespective of whether the slave/advertiser needsto transmit data.

It is another object of the invention to provide a low-power/low-energyway of propagating messages between BLE-enabled mobile wireless devicesand sensors without requiring hardware changes or firmware changes tothe BLE-enabled devices.

It is another object of the invention to provide a low-power/low-energyway of propagating messages between BLE-enabled mobile wireless devicesand sensors while efficiently avoiding the effects of drift betweeninternal clock signals in various slave/advertiser devices andmaster/scanner devices.

Briefly described, and in accordance with one embodiment, the presentinvention provides a BLE network includes a first piconet (A) includinga first master scanner (3-1) and a first group of low-powerslave/advertisers (5-1,2 . . . 5) for transmitting wirelessadvertisements and for establishing wireless connections, respectively,with the first master/scanner. Circuitry (3,55) in the firstmaster/scanner wireless scans to detect an advertisement (58,62)transmitted by a first slave/advertiser (5-1) of the first group andtransmits a connection request (58,62) in response to the detecting, andtransmits a schedule (60) for subsequent advertisements after an initialadvertisement by the first slave/advertiser to thereby completesynchronization of the first master/scanner with the firstslave/advertiser. Circuitry (5,39) in the first slave/advertisertransmits the initial advertisement (42), receives an acceptance aresulting connection request, establishing an association (44) with thefirst master scanner, and then causes the first slave/advertiser to goto sleep in a low-power mode, to wake up and transmit subsequentadvertisements only according to the schedule (50), and to acceptresulting connection requests from the first master/scanner if data isavailable to be advertised, transmitting the available data to the firstmaster/scanner, and going back to sleep.

In one embodiment, the invention provides a BLE (Bluetooth low energy)network including a first piconet (A) including a first master scanner(3-1) and a first group of low-power slave/advertisers (5-1,2 . . . 5)for transmitting wireless advertisements and for establishing wirelessconnections, respectively, with the first master/scanner (3-1);circuitry (3 in FIG. 7, 55 in FIG. 10) in the first master/scanner (3-1)for wireless scanning to detect an advertisement (58,62 in FIG. 10)transmitted by a first slave/advertiser (5-1) of the first group (5-1,2. . . 5) and transmitting a connection request (58,62 in FIG. 10) inresponse to the detecting, and transmitting a schedule (60 in FIG. 10)for subsequent advertisements after an initial advertisement by thefirst slave/advertiser (5-1) to thereby complete synchronization of thefirst master/scanner (3-1) with the first slave/advertiser (5-1); andcircuitry (5 in FIG. 8,39 in FIG. 9) in the first slave/advertiser (5-1)for transmitting the initial advertisement (42 in FIG. 9), receiving andaccepting a resulting connection request, establishing an association(44 in FIG. 9) with the first master scanner (3-1), after which thefirst slave/advertiser (5-1) goes to sleep in a reduced power mode,waking up and transmitting subsequent advertisements only according tothe schedule (50 in FIG. 9), and accepting resulting connection requestsfrom the first master/scanner (3-1) if data is available to beadvertised, transmitting the available data to the first master/scanner(3-1), and going back to sleep.

In a described embodiment, the connection request is the initialconnection request and is transmitted by the first master/scanner (3-1)and is accepted and acknowledged by the first slave/advertiser (5-1) toestablish association and synchronization between the firstmaster/scanner (3-1) and the first slave/advertiser (5-1).

In one embodiment, the first slave/advertiser (5-1) accepts a connectionrequest after the association has been established only if the firstslave/advertiser (5-1) has data available to be advertised.

In one embodiment, the first master/scanner (3-1) transmits connectionrequests only if the advertisements meet a predetermined RSSI (receivedsignal strength indicator) requirement. In one embodiment, accepting aconnection request by the slave/advertiser (5-1) causes it to establisha temporary wireless connection between it and the first master/scanner(3-1).

In one embodiment, the schedule requires a predetermined number ofallowed advertisements by the first slave/advertiser (5-1) before itinitiates resynchronization of the first slave/advertiser (5-1) with thefirst master/scanner (3-1) to compensate drift between internal clocksignals of the first slave advertiser (5-1) and the first master/scanner(3-1), respectively.

In one embodiment, the BLE low energy network includes circuitry (3 inFIG. 7) in the first master/scanner (3-1) for transmitting anadvertisement containing aggregated data received from the firstslave/advertiser (5-1) to a second master/scanner (3-2).

In one embodiment, the BLE low energy network includes circuitry (3 inFIG. 7) in the first (3-1) and second (3-2) master/scanners forselectively either (1) communicating the aggregated data to the secondmaster/scanner (3-2) according to a non-continuous predeterminedschedule in a BLE mode of operation, or (2) communicating the aggregateddata from the first slave/advertiser (5-1) to the second master/scanner(3-2) in a manner that is continuous and not according to a schedule.

In one embodiment, the BLE low energy network includes a second piconet(B) including the second master scanner (3-2) and a second group oflow-power slave/advertisers (5-6,7) for transmitting wirelessadvertisements and establishing wireless connections, respectively, withthe second master/scanner (3-2), the second piconet (B) also includingcircuitry (e.g., 3 in FIG. 7, 55 in FIG. 10) in the secondmaster/scanner (3-2) for wireless scanning to detect an advertisement(58,62 in FIG. 10) transmitted by a second slave/advertiser (5-6) of thesecond group (5-6,7) and transmitting a connection request (58,62) inresponse to the detecting, and transmitting a schedule (60 in FIG. 10)for subsequent advertisements after an initial advertisement by thesecond slave/advertiser (5-6); and circuitry (5 in FIG. 8,39 in FIG. 9)in the second slave/advertiser (5-6) for transmitting the initialadvertisement (42 in FIG. 9), receiving and accepting a resultingconnection request, establishing an association (44 in FIG. 9) with thesecond master scanner (3-2), and then causing the secondslave/advertiser (5-6) to go to sleep in a low-power mode, waking up andtransmitting subsequent advertisements only according to the schedule(50 in FIG. 9), and accepting resulting connection requests from thesecond master/scanner (3-2) if data is available to be advertised,transmitting the available data to the first master/scanner (3-2),causing the second slave/advertiser (5-6) to go back to sleep; andcircuitry in the second master/scanner (3-2 in FIG. 5) for transmittingan advertisement containing aggregated data received from the firstslave/advertiser (5-6) to a third master/scanner (3-3).

In one embodiment, the first master/scanner (3-1) operates to cull aconnection with another master/scanner based on RSSI levels ofadvertisements received from the other master/scanner and the number ofhops between master/scanners along a particular route required foraggregated data from the first slave/advertiser of the first group(5-1,2 . . . 5) to reach a destination of the aggregated data.

In one embodiment, the first slave/advertiser (5-1) can only advertiseaccording to the schedule after the association and synchronization havebeen performed.

In one embodiment, the aggregated data is accumulated in a data packetthat includes information identifying a slave/scanner that firstadvertised the aggregated data and also identifies an upstreamdestination of the aggregated data.

In one embodiment, if both the first master/scanner (3-1) and the secondmaster/scanner (3-2) are transmitting the same particular set ofaggregated data to a third master/scanner (3-3 in FIG. 5) and dataloading of the second master/scanner (3-2) is greater than data loadingof the first master/scanner (3-1), then the culling includes operatingthe third master/scanner (3-3) to cause the second master/scanner (3-2)to stop sending the particular set of aggregated data to the thirdmaster/scanner (3-3).

In one embodiment, BLE low energy network operates to perform repeatedscanning and advertising operations of master/scanners along anestablished route including the first (3-1) and second (3-2)master/scanners until the aggregated data reaches a predetermineddestination.

In one embodiment, the invention provides method for operating a BLE(Bluetooth low energy) network to reduce energy consumption, the methodincluding providing a first piconet (A) including a first master scanner(3-1) and a first group of low-power slave/advertisers (5-1,2 . . . 5)for transmitting wireless advertisements and for establishing wirelessconnections, respectively, with the first master/scanner (3-1);operating a first slave/advertiser (5-1) of the first group (5-1,2 . . .5) to transmit an initial advertisement (42 in FIG. 9); operating thefirst master/scanner (3-1) in a scanning mode to detect the initialadvertisement (58,62 in FIG. 10) and to transmit a correspondingconnection request (58,62 in FIG. 10) in response to the detecting;operating the first slave/advertiser (5-1) to receive and accept thecorresponding connection request (58,62 in FIG. 10) and establish anassociation (44 in FIG. 9) with the first master scanner (3-1);operating the first master/scanner (3-1) to transmit to the firstslave/advertiser (5-1) a schedule (60 in FIG. 10) for subsequentadvertisements to thereby synchronize (44 in FIG. 9) the firstmaster/scanner (3-1) with the first slave/advertiser (5-1), and thencausing the first slave/advertiser (5-1) go to sleep (48 in FIG. 9) in alow-power mode (52 in FIG. 9); operating the first slave/advertiser(5-1) to wake up and transmit (50 in FIG. 9) subsequent advertisementsonly according to the schedule and operating the first master/scanner(3-1) to simultaneously scan for the subsequent advertisements (62 inFIG. 10) according to the schedule (60 in FIG. 10) and transmitconnection requests corresponding to the subsequent advertisements, andoperating the first slave/advertiser (5-1) to accept the correspondingconnection requests (44 in FIG. 9) from the first master/scanner (3-1)if the first slave/advertiser (5-1) has data available to be advertised;and operating the first slave/advertiser (5-1) to advertise theavailable data (50 in FIG. 9) to the first master/scanner (3-1) andoperating the first master/scanner (3-1) to aggregate the advertisedavailable data (62 in FIG. 10).

In one embodiment, the method includes operating the firstmaster/scanner (3-1) to transmit connection requests only if theadvertisements meet a predetermined RSSI (received signal strengthindicator) requirement (58 in FIG. 10).

In one embodiment, the schedule requires a predetermined number ofallowed advertisements by the first slave/advertiser (5-1) before itinitiates resynchronization (46 in FIG. 9) of the first slave/advertiser(5-1) with the first master/scanner (3-1) to compensate drift betweeninternal clock signals of the first slave advertiser (5-1) and the firstmaster/scanner (3-1), respectively.

In one embodiment, the method includes a second piconet (B) including asecond master scanner (3-2) and a second group of low-powerslave/advertisers (5-6,7) for transmitting wireless advertisements andestablishing wireless connections, respectively, with the secondmaster/scanner (3-2), the second piconet (B) being substantially similarto the first piconet (A).

In one embodiment, the method includes operating the firstmaster/scanner (3-1) to cull a connection with another master/scannerbased on RSSI levels of advertisements received from the othermaster/scanner and the number of hops between master/scanners along aparticular route required for aggregated data from the firstslave/advertiser of the first group (5-1,2 . . . 5) to reach adestination of the aggregated data (64 in FIG. 10).

In one embodiment, the culling includes operating the firstmaster/scanner (3-1) to command another master/scanner having heavy dataloading to stop sending redundant data to the first master/scanner(3-1).

In one embodiment, the method includes repeating scanning andadvertising operations of master/scanners along an established routeuntil the aggregated data reaches a predetermined destination.

In one embodiment, the invention provides a system for operating a BLE(Bluetooth low energy) network to reduce energy consumption, including afirst piconet (A) including a first master scanner (3-1) and a firstgroup of low-power slave/advertisers (5-1,2 . . . 5) for transmittingwireless advertisements and for establishing wireless connections,respectively, with the first master/scanner (3-1); means (28-2,42) foroperating a first slave/advertiser (5-1) of the first group to transmitan initial advertisement (42); means (28-1,58) for operating the firstmaster/scanner (3-1) in its scanning mode to detect the initialadvertisement (58,62) and to transmit a corresponding connection request(58,62) in response to the detecting; means (28-2,44) for operating thefirst slave/advertiser (5-1) to receive and accept the correspondingconnection request and establish an association (44) with the firstmaster scanner (3-1); means (28-1,60) for operating the firstmaster/scanner (3-1) to transmit to the first slave/advertiser (5-1) aschedule (60) for subsequent advertisements to thereby synchronize thefirst master/scanner (3-1) with the first slave/advertiser (5-1), andmeans (28-2,48,52) for then causing the first slave/advertiser (5-1) goto sleep in a low-power mode; means (28-2,46) for operating the firstslave/advertiser (5-1) to wake up and transmit subsequent advertisementsonly according to the schedule and means (28-1,62) for operating thefirst master/scanner (3-1) to simultaneously scan for the subsequentadvertisements according to the schedule (50), means (28-1,62) foroperating the first master/scanner (3-1) to transmit connection requestscorresponding to the subsequent advertisements, and means (28-2,5) foroperating the first slave/advertiser (5-1) to accept the correspondingconnection requests from the first master/scanner (3-1) if the firstslave/advertiser (5-1) has data available to be advertised; and means(28-2,46) for operating the first slave/advertiser (5-1) to advertisethe available data to the first master/scanner (3-1) and means (28-1,62)for operating the first master/scanner (3-1) to aggregate the advertisedavailable data.

In one embodiment, the system includes means (28-1,58) for operating thefirst master/scanner (3-1) to transmit connection requests only if theadvertisements meet a predetermined RSSI (received signal strengthindicator) requirement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating conventional communication between apair of piconets.

FIG. 2 is a diagram illustrating communication between a pair ofpiconets in accordance with the present invention.

FIG. 3 is a diagram illustrating a BLE sensor net low-power associationprocess during operation of the piconets of FIG. 2.

FIG. 4 is a diagram illustrating a BLE sensor scanning synchronizationprocess during operation of the piconets of FIG. 2.

FIG. 5 is a diagram illustrating a route culling process duringoperation of the piconets of FIG. 2.

FIG. 6 is a diagram illustrating an acknowledgment and phasesynchronization process during operation of the piconets of FIG. 2.

FIG. 7 is a block diagram of a master/scanner as shown in FIG. 2.

FIG. 8 is a block diagram of a slave/advertiser as shown in FIG. 2.

FIG. 9 is a flowchart of an operating algorithm for a slave/advertiser.

FIG. 10 is a flowchart of an operating algorithm for a master/scanner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 shows an improved, very low-power scatternet 1 including apiconet A and a piconet B each including a master/scanner device capableof wireless communication with a number of nearby slave/advertiserdevices. In piconet A, master/scanner 3-1 is capable of wirelesscommunication with advertisers 5-1, 5-2, 5-3, 5-4, and 5-5 throughwireless links 2-1, 2-2, 2-3, 2-4, and 2-5, respectively. Similarly, inpiconet B, master/scanner 10-2 is capable of wireless communication withadvertisers 5-6 and 5-7 through wireless links 2-6 and 2-7,respectively. Each slave/advertiser can have a wireless link with onlyone master/scanner. Each slave/advertiser and each master/scannerincludes at least a transceiver and a processor with integrated memoryrunning the BLE protocol stack. The BLE protocol stack consists ofsoftware that implements the BLE protocol as defined by the Bluetooth4.0 core specification.

As shown in FIG. 7, a master/scanner 3 of the kind shown in FIG. 2includes a transceiver system 25-1 coupled by a bus 30-1 to a controlcircuit 27-1. Control circuit 27-1 is connected by a bus 31-1 to aprocessor 26-1, which is connected by a bus 33-1 to a block 28-1including a memory and stored scanning mode and advertiser modealgorithms along with stored standard BLE 4.0 protocol information.Block 28-1 is coupled by bus 32-1 to control circuit 27-1. Everything inmaster/scanner 3 may be conventional, except for updated firmware intransceiver system 25-1, which may be a pre-existing transceiver system.The updated firmware enables master/scanner 3 to operate in accordancewith the slave-master association and synchronization methodologysubsequently described herein and also enables master/scanner 3 tooperate in accordance with the master/scanner-to-master/scannersynchronization and culling methodology subsequently described herein.

Similarly, and as shown in FIG. 8, a slave/advertiser 5 of the kindshown in FIG. 2 includes a transceiver system 25-2 coupled by a bus 30-2to a control circuit 27-2. Control circuit 27-2 is connected by a bus31-2 to a processor 26-2, which is connected by a bus 33-2 to a block28-2 including a memory and stored scanning mode and advertiser modealgorithms along with stored standard BLE 4.0 protocol information.Block 28-2 is coupled by bus 32-2 to control circuit 27-2. Everything inslave/advertiser 5 may be conventional, except for updated firmware intransceiver system 25-2, which may be a pre-existing transceiver system.The updated firmware enables slave/advertiser 5 to operate in accordancewith the slave-master association and synchronization methodologysubsequently described herein and also enables slave/advertiser 5 tooperate in accordance with the slave/advertiser-to-master/scannerassociation and synchronization methodology subsequently describedherein.

Master/scanner 3-1 in piconet A communicates with master 3 in piconet Bthrough a wireless link 7. In piconet A, master/scanner 3-1 cansynchronize with any of the slave/advertisers 5-1,2 . . . 5 in piconetA, for example to establish wireless link 2-1 with slave/advertiser 5-1as indicated by reference numeral 15, and then may perform two-waywireless data communication with a slave/advertiser, for example withslave/advertiser 5-2 as indicated by reference numeral 17. That is,piconet A is basically a collection of slave/advertisers that arescanned by master/scanner 3-1 which can also wirelessly connect to themaster/scanner 3-2 of piconet B. Scatternet 1 could include many morepiconets that communicate with each other in essentially the samemanner.

In piconets such as A and B, all of the master/scanner devices are“powered” devices, which means that they all are powered by acorresponding power supply that is sufficient to allow themaster/scanner to operate continuously. Each slave/advertiser device isa very low-power device supplied by its power supply (such as a smallbattery or a small solar panel or other energy harvester) that does notneed to be capable of allowing continuous operation of theslave/advertiser device. The slave/advertiser needs to spend asubstantial amount of time in a “sleep” mode to conserve its energysource for operation when the slave/advertiser wakes up. (For example, aslave/advertiser may have a rechargeable battery and a very small solarpanel (e.g., approximately 1 centimeter squared), so theslave/advertiser has a very “tight” energy budget, whereas themaster/scanner may have a much larger solar panel and rechargeablebatteries that enable it to operate continuously. The slave/advertiserperiodically wakes up and sends out an advertisement.

Each master/scanner acknowledges the advertisement by transmitting aconnection request, and if the slave/advertiser wants to have moreelaborate communication, the connection request is accepted by theslave/advertiser and a temporary wireless connection between theslave/advertiser and the master/scanner is established. (If theslave/advertiser tries to send an advertisement at other times, themaster/scanner will not acknowledge it; and the slave/advertiser willconnect with the master/scanner only after the slave/advertiser wakes upat its next scheduled time.)

Slave/advertisers in a piconet are very low energy devices which wouldnot ordinarily be used to aggregate data generated by otherslave/advertisers and then connect to the master/scanner of a differentpiconet as shown in the network of Prior Art FIG. 1.

The BLE standard is utilized as a starting point for the methodsubsequently described with reference to FIGS. 3-6 because thelowest-power available radio standard for wireless communication isneeded in order to maintain interoperability with various Bluetoothdevices such as “smart phones”. In the method of operation of piconets Aand B in FIG. 2, each slave/advertiser initially transmits anadvertisement whenever it “wishes”, irrespective of any predeterminedtime intervals and/or frequency or “periodicity”, and in response themaster/scanner of each piconet initially is “associated” with eachslave/advertiser in the piconet, and then “dictates” the starting timeand duration of future advertisements by that slave/advertiser during aprocess of synchronization with of that slave/advertiser. Themaster/scanner then knows when to “wake up” to scan for advertisementsby the various slave/advertisers in the piconet. This avoids the needfor every slave/advertiser to periodically wake up (for example, every 4seconds) to advertise as required by standard BLE operation, and therebyavoids the periodic power consumption that would otherwise occur duringpre-scheduled periodic wake-up intervals during which theslave/advertiser has nothing to advertise.

Also, as subsequently explained, after a predetermined number ofadvertisements by a slave/advertiser, the master/scanner must“resynchronize” with the slave/advertiser to compensate “drift” betweenthe internal clock signals of the master/scanner and theslave/advertiser.

FIG. 3 shows a configuration 1-1 of scatternet 1 in FIG. 2 wherein thevery low power slave/advertisers 5-1, 5-2, . . . 5-5 in piconet Asimilarly become associated with master/scanner 3-1, and wherein thevery low power slave/advertisers 5-6 and 5-7 in piconet B become“associated” with master/scanner 3-2. The wirelessly transmittedadvertisements by low-power slave/advertisers 5-1, 5-2, . . . 5-5,respectively, occur prior to becoming associated at unsynchronized orsomewhat random times, and master/scanner 3-1 responds to the first suchadvertisement having a signal strength that exceeds a predetermined RSSI(Received Signal Strength Indicator) threshold by sending a “connectionrequest” to the originating slave/advertiser. Master/scanner 3-1 theninitiates a synchronization procedure to synchronize and thereby“associate” that first slave/advertiser with master/scanner 3-1. Theother slave/advertisers in piconet A eventually also become associatedwith master/scanner 3-1 in the same manner. Similarly, low-powerslave/advertisers 5-6 and 5-7 in piconet B eventually become associatedwith master/scanner 3-2 in essentially the same way.

A low-power network or piconet “node” is referred to herein as aslave/advertiser, although technically the node is not considered to bea slave until a wireless communication connection is actuallyestablished with a master/scanner. Also, a network or piconet node isnot technically considered to be a master/scanner until a wirelessconnection is established between it and a slave/advertiser.

At the beginning of a relevant time interval, all of theslave/advertisers initially are advertising during unsynchronizedintervals and have the ability to “associate” with any master/scannerthat is close enough for a valid wireless connection with theslave/advertisers. A slave/advertiser is said to be “associated” with amaster/scanner after it has established a wireless connection with thatmaster/scanner. There is a suitable predetermined threshold for aconventional RSSI which must be exceeded by the transmittedadvertisement signals as they are received by the master/scanner, inorder to establish a valid wireless connection with a master/scanner. Ifa particular slave/advertiser is the first slave/advertiser to meet theRSSI threshold of a particular master/scanner, that master/scanner sendsback a “connection request”. The connection request is sent from themaster/scanner to a slave/advertiser in response to an advertisement bythe slave/advertiser in order to schedule periodic wake-up times andcommunication times in accordance with a BLE standard. Note that amaster/scanner is in its scanning mode both while it receives/detects anadvertisement and also when it sends a connection request.

The slave/advertiser then establishes an initial connection with thatmaster/scanner and thereby becomes associated with that master/scanner.A slave/advertiser can associate with only one master/scanner, andcannot wirelessly connect to any other master/scanner. (Also, an“associated” slave/advertiser cannot wirelessly connect to anotherslave/advertiser.) As soon as the slave/advertiser becomes associatedwith the master/scanner, the master/scanner dictates or imposes aschedule of starting times or periodicity of starting times ofpre-established time intervals during which the slave/advertiser musttransmit its subsequent advertisements whenever it has data available totransmit. If the slave/advertiser has no data available to transmit, itcan immediately go back to its very-low-power “sleep” mode.

The master/scanner knows when to go into its scanning mode according tothe above-mentioned schedule it imposed in order to receive subsequentadvertisements from the associated slave/advertiser. Initially, themaster/scanner wirelessly and continuously scans and detects any slaveadvertisement and in response transmits a corresponding connectionrequest. The slave/advertiser wirelessly connects with themaster/scanner to receive the connection request and then themaster/scanner transmits the advertisement “schedule”. If theslave/advertiser has more data to send, it will “accept” a connectionrequest received after the subsequent advertisement. Otherwise, theslave/advertiser will just put its present data in the advertisementpacket and use the connection request as an acknowledgment. If aconnection request is not received after the advertisement, theslave/advertiser retransmits the advertisement and accepts a resultingresponsive subsequent connection request transmitted by themaster/scanner. If the master/scanner wishes to send data to aslave/advertiser, the master/scanner does not send a connection requestfollowing the advertisement. The master/scanner subsequently sends thedata through the established wireless connection according to thepre-established schedule. Master/scanners can advertise aggregated datato other master/scanners during previously established advertisementperiods that have been “agreed upon” with those master/scanners. (Seethe flow chart in subsequently described FIG. 9.)

It should be understood that the two piconets together represent a“static environment”, meaning that neither the master/scanners norslave/advertisers are physically moving. Once the master/scanner of apiconet has scanned for a sufficiently long amount of time, it utilizesremaining available time intervals (which have not been allocated forthe purpose of scanner-to-slave/advertiser synchronization) to functionin its own advertising mode so that it can wirelessly connect with andsynchronize with master/scanners of other piconets. It also should beunderstood that all of the slave/advertisers and the master/scanner in apiconet are originally unsynchronized and the slave/advertisersinitially are advertising at somewhat random, unsynchronized timesaccording to the needs of the various slave/advertisers. When eachslave/advertiser wirelessly connects to and becomes associated with aparticular master/scanner, that slave/advertiser and that master/scannermust become synchronized with each other. Also, each master/scanner ineach piconet functions in arranging its various wireless connections ina way that minimizes the number of times that the master/scanner needsto occasionally resynchronize with its various slave/advertisers,respectively, to avoid the effects of drift between its internal clocksignal phase and the internal clock signal phase of its associatedslave/advertisers and also leaves a sufficiently large remaining timeinterval to allow the master/scanner to advertise to master/scanners ofother piconets. During the master-to-slave synchronization procedure,the master/scanner dictates to an associated slave/advertiser when it isto wake up and start its next advertisement and how much time is allowedfor that advertisement. (Those values typically are determined initiallyby a centrally controlled network to the piconets, and can be updated.)

The information in the advertisement packet indicates that the packet isbeing transmitted by a master/scanner that wants to connect to themaster scanner of another piconet. (An advertisement contains 32-39bytes of data in an advertisement packet for transmission by amaster/scanner.) Other such master/scanners that are close enough toreceive the transmitted advertisement packet signal then recognize thatit has been transmitted from a master/scanner rather than aslave/advertiser and can, if appropriate RSSI signal criteria are met,synchronize and establish a wireless connection between themaster/scanners. This process continues until all master/scanners withinrange of each other synchronize and establish wireless connections witheach other, achieving what is referred to as “full connection” of thepiconets.

As indicated in the flowchart of FIG. 9, reference numeral 39 designatesan embodiment of an operating algorithm stored in block 28-2 ofslave/advertiser 5 in FIG. 8. Slave/advertiser algorithm 39 begins atlabel 40 in FIG. 9. The slave/advertiser transmits an unsynchronizedinitial advertisement and waits for a connection request, as indicatedin block 42. Then, as indicated in block 44, if the slave/advertiser 5receives a timely connection request from a master/scanner which hasreceived the initial advertisement, the slave/advertiser 5 in FIG. 8 mayaccept the connection request and thereby do its part to associate withand synchronize with the master/scanner. If the slave/advertiser 5 doesnot receive a timely connection request, it waits for an appropriateamount of time and re-transmits the initial advertisement. As indicatedin block 46, once the association of the slave/advertiser 5 in FIG. 8with the master/scanner has been accomplished, the slave/advertiser 5then receives and stores a schedule for subsequent advertisements (alongwith a predetermined number of advertisements which the slave/advertiser5 must perform before a re-synchronization operation must be performed),in order to complete the association and synchronization (orre-synchronization) with the master/scanner. Then the algorithm goes toblock 48 and causes the slave/advertiser 5 in FIG. 8 to go to sleep intoa very low power mode. After that, the slave/advertiser 5 wakes up onlyperiodically at the scheduled times, and advertises or transmits anyavailable data it has to the associated master/scanner, as indicated inblock 50, and then goes back to sleep as indicated in block 52.

FIG. 4 shows a configuration 1-2 of scatternet 1 in FIG. 2 wherein“powered” master/scanner 3-1 in piconet A becomes “synchronized” withmaster/scanner 3-2 in piconet B. Wireless connection 7 betweenmaster/scanners 3-1 and 3-2 in FIG. 2 is shown in FIG. 4 to includewireless signal 7A transmitted from master/scanner 3-1 to master/scanner3-2 and wireless signal 7B transmitted from master/scanner 3-2 tomaster/scanner 1. The scanner synchronization procedure includesmaster/scanner 3-1 going into its advertising mode after it hasaggregated data which it has received from any of its variousslave/advertisers 5-1,2 . . . 5 to transmit or forward the received andaggregated data to other master/scanners outside of piconet A inadvertisement packets at previously agreed-upon advertisement timeintervals. A master/scanner acts as an advertiser when sending suchaggregated advertisement data to another master/scanner. This process ofadvertising data by slave/advertisers at the scheduled times, receptionand aggregation of the advertised data by an associated master/scanner,and advertising or relaying of the aggregated data packets by the“associated” master/scanner to another master/scanner, is repeated untilthe data is received by a master/scanner that is connected to a wired ornon-BLE network such as a Wi-Fi network.

In FIG. 4, signal 7A is transmitted by master/scanner 3-1 during a“non-established” or “non-negotiated” or “random” low-power timeinterval to trigger a two-way process by means of which the point intime is established at which the master/scanner 3-1 will be advertisingor transmitting aggregated data and the master/scanner 3-2 will bescanning or receiving data. After this scanner synchronization processis complete, master/scanner 3-1 can aggregate data from any of thevarious slave/advertisers in piconet A and transmit it to master/scanner3-2, which transmits the aggregated data in an advertisement (i.e., anadvertisement packet or a standard connection interval packet) to themaster/scanner of another piconet or to an upstream network.

Once the master/scanner of a particular piconet has synchronized withall of its slave/advertisers that still include a “request forassociation” message in an un-sent advertisement, then themaster/scanner starts sending out advertisements to othermaster/scanners during the above-mentioned remaining time interval.During that period of time, master/scanners of other piconets mayreceive such advertisements in new or already-established wirelessconnections.

In FIG. 4, wireless connections 7-1 and 7-2 are established between thetwo master/scanners 3-1 and 3-2. Time intervals are established whereineach master/scanner can function as a scanner, respectively, during acorresponding particular time interval and during correspondingremaining time intervals each master/scanner can function as anadvertiser. That enables master/scanners 3-1 and 3-2 to send or exchangeaggregated data in multiple packets between each other, one via theupstream wireless connection 7-1 and the other via the downstreamwireless connection 7-2. At that point, wireless connection timeintervals can be established during which a master/scanner that hasaggregated data can forward it to the master/scanner of another piconetor to an upstream network. For example, if the connection intervals areestablished to be 30 seconds and master/scanner 3-2 wants to receiveaggregated data from any of the slave/advertisers 5-1,2 . . . 5 inpiconet A, then master/scanner 3-2 in piconet B will, at the assignedperiodicity or frequency, establish a wireless connection withmaster/scanner 3-1 and transmit its aggregated data to master/scanner3-2. Master/scanner 3-1 in piconet A will also accept any otheraggregated data that master/scanner 3-2 in piconet B has available forany of the slave/advertisers of master/scanner 3-1 and then redistributethat data to those slave/advertisers.

As indicated in the flowchart of FIG. 10, reference numeral 55designates an embodiment of an operating algorithm stored in block 28-1of master/scanner 3 of FIG. 7. Master/scanner algorithm 55 begins atlabel 56, and goes to block 58, wherein the master/scanner 3 of FIG. 7operates in its scanning mode to receive any initial advertisement if itmeets a predetermined RSSI threshold criteria, and if the initialadvertisement does meet the RSSI criteria the master/scanner thentransmits a connection request to the sending slave/advertiser to enableit to associate with and become synchronized with the master/scanner.The master/scanner 3 of FIG. 7 also operates in its scanning mode toreceive any other initial advertisements from other associatedslave/advertisers and in response sends connection requests to them toenable them to become associated with the master/scanner. Themaster/scanner 3 of FIG. 7 also sends connection requests to any of itsalready-associated slave/advertisers. As indicated in block 60, themaster/scanner 3 receives an acceptance/acknowledgment transmitted fromany slave/advertiser that has accepted a connection request sent by themaster/scanner 3 of FIG. 7 in response to an initial advertisement bythat slave/advertiser and then sends a schedule for subsequentadvertisements by the slave/advertiser and also sends a predeterminednumber equal to the number of additional advertisements theslave/advertiser must transmit before initiating a re-synchronizationoperation with the master/scanner.

Master/Scanner algorithm 55 then goes to block 62, and themaster/scanner 3 of FIG. 7 operates in its scanning mode in accordancewith the schedule previously sent to the slave/advertiser toreceive/detect any new advertisements from the slave/advertiser, sendcorresponding connection requests, receive acknowledgments oracceptances of the connection requests, and then aggregate datacontained in the new advertisement in a data packet. Then, as indicatedin block 64, the master/scanner 3 then goes into its advertising modeand advertises for another master/scanner to forward the aggregated datato an upstream (or downstream) master/scanner via an existing wirelessconnection, or the master/scanner creates a new wireless connection withanother master/scanner 3 and forwards the aggregated data to it via thenew wireless connection, after culling any redundant wirelessconnections in order to obtain an optimized wireless path from themaster/scanner 3 aggregating the data to the final destination of thedata using RSSI and the number of “hops” as culling criteria.

After the foregoing procedure has been repeated to achieve “fullconnection” (which may include a number of redundant or unnecessaryestablished wireless connections between master/scanners along one ormore routes to an upstream destination of an advertisement), thenredundant or unnecessary wireless connections are “culled”, assubsequently explained with respect to FIG. 5. Data aggregated from theindividual slave/advertisers is “piped” upstream through one or moremaster/scanners, typically until the data reaches an intended upstreamnetwork. Essentially the same technique also is used for communicationfrom the upstream network to downstream master/scanners and theirrespective slave/advertisers.

It should be appreciated that transmitted data includes informationcapable of identifying intended destinations for the data once it isaggregated. The destination-identifying information may explicitlyidentify the desired data destinations, or it may be implicit from theorder in which the aggregated data is arranged. The aggregated datapacket thus includes information that lets upstream master/scanners andslave/advertisers know where the various packets of aggregated data camefrom and/or the final intended destination for the various packets ofaggregated data. Often, the aggregated data is relayed to an upstreamexternal network via one or more master/scanners, then is analyzed, andthen is transmitted back from a centralized source to the originatingslave/advertiser to accomplish a control function or the like. (However,it is possible for a master/scanner to scan its slave/advertisers in onepiconet, and obtain data from them for the purpose of transmitting thatdata along a route to a master/scanner in another piconet and from it toa slave/advertiser in that piconet.) The described embodiment of theinvention is particularly suitable for occupancy sensing and controlapplications in various industrial control applications.

FIG. 5 shows a simplified network configuration including multipleestablished wireless “routes” that provide a “full connection” betweenthree master/scanners 3-1, 3-2, and 3-3 of three separate piconets. (Forconvenience, the “associated” slave/advertisers in the three piconetsare not shown.) Master/scanner 3-1 is wirelessly connected tomaster/scanner 3-3 by wireless connections 2-1 and 2-2, and also iswirelessly connected to master/scanner 3-2 by wireless connections 2-3and 2-4. Master/scanner 3-2 is wirelessly connected to master/scanner3-3 by wireless connections 2-5 and 2-6. Master/scanner 3-3 is connectedto an upstream network 10 by means of a connection 9, which may be awireless or physical connection 9. Connections which are not redundant(or are not required for other reasons) are eliminated on the basis of aculling process based on the highest RSSI level and the least number of“hops” (i.e., re-transmissions of data packet signals required to reachthe standard network).

In FIG. 5 the system goes through and culls or eliminates unnecessarywireless connections between master/scanners. Starting with the “fullyconnected” network of piconets in which some of the established wirelessconnections are redundant or unnecessary, the culling process removesall but the most desired or optimum wireless connections betweenindividual master/scanners in the various piconets, respectively, untilthe desired BLE connection between various slave/advertisers and acentralized processor on an upstream network 10 has been achieved. InFIG. 5, the result of culling a redundant wireless path includingwireless connections 2-3 and 2-4 between master/scanners 3-1 and 3-2 isindicated by the “X” drawn through wireless connections 2-3 and 2-4.

The culling process can be thought of as starting with a network thatincludes a tree-like structure of wireless paths some of which areredundantly or non-optimally connected to a trunk of the tree-likestructure and removing all but the desired wireless paths so as toestablish a single route in which the number of times that the data isre-transmitted to reach its destination is reduced.

The culling criteria, including the RSSI and the number of hops, areapplied at each master/scanner node of the possible wireless connectionroute being evaluated, and the one having the combination of the highestRSSI values and the lowest number of hops between the originatingmaster/scanner and the upstream network 10 is retained, and theremaining paths are eliminated. (A “hop” corresponds to a transmissionfrom one master/scanner to another. For example, if a slave/advertisersends data to master/scanner 3-1, which then forwards it tomaster/scanner 3-2 and master/scanner 3-2 then transmits that data tothe external network, the route includes 2 hops. That is, the number ofhops is equal to the number of data retransmissions from the originatingmaster/scanner to the intended destination of the data.)

The culling is performed locally, rather than in a remote upstreamnetwork, in order to eliminate multipaths (i.e., redundant wirelessconnections) between the master/scanners along a desired route to aspecified data destination. For example, if a master/scanner isreceiving the same aggregated data from two other master/scanners, ittells one of them to stop forwarding that subset of data. The decisionas to which scanner to command to stop redundant transmissions is basedon data “loading”. For example, if a master/scanner is sending twice asmuch data as another master/scanner, the one having the larger amount ofdata loading is told or commanded to stop forwarding the redundant data.The more heavily loaded master/scanner is, in effect, told to stopsending redundant data. For example, if both the first master/scanner3-1 and the second master/scanner 3-2 are transmitting the sameparticular set of aggregated data to a third master/scanner 3-3 in FIG.5 and data loading of the second master/scanner 3-2 is greater than dataloading of the first master/scanner 3-1, then the culling includesoperating the third master/scanner 3-3 to tell the second master/scanner3-2 to stop sending the particular set of aggregated data to the thirdmaster/scanner 3-3.

FIG. 6 is a timing diagram that illustrates the time interval betweensuccessive advertisements by a slave/advertiser. The slave/advertisersends out an advertisement during the interval 11-1, and the receivingmaster/scanner sends a “connection request” during the interval 11-2.The connection request will be accepted by the slave/advertiser if ithas data to transmit. Otherwise, the connection request will be rejectedby the slave/advertiser. The time interval 11-3 extends from thebeginning of the advertisement during the interval 11-1 to the beginningof the next advertisement by the same slave/advertiser during theinterval 11-4.

Note that after the first synchronization procedure by a master/scannerwith an associated slave/advertiser, the master/scanner establishes inthe slave/advertiser a number (e.g., 20) of subsequent advertisementsafter which the slave/advertiser and master/scanner are required to“resynchronize” in order to adjust or recalibrate the time interval 11-3between successive advertisements so as to account for or compensate forinternal drift between the internal clock signals of theslave/advertiser and the master/scanner during the 20 (in this example)successive advertisements. (The internal clock signal drift occursbecause the internal clock signals are based on different crystaloscillators which ordinarily have slightly different oscillatingfrequencies.) Such clock signal drift is cumulative and therefore willeventually cause the time interval 11-3 to change, possibly (if there isno resynchronization) causing it to overlap with a previously allocatedtime interval during which the master/scanner must function as anadvertiser of aggregated data. The resynchronization allows theslave/advertiser to know when to wirelessly connect with themaster/server to initiate the resynchronization procedure.

Scatternet 1 of FIG. 2 has the previously mentioned “dual mode”capability, which supports “classic” Bluetooth standard operation aswell as operation in accordance with the BLE low energy standard. Indual mode operation, the multiple the master/scanners which form a“core” of the network have the option of either communicating with eachother as previously with respect to FIGS. 3-10 above or communicatingwith each other using “classic” Bluetooth operation, which is“continuous” in the sense that the communication between themaster/scanners not involve operating according to a schedule aspreviously described. However, in either mode the communication betweenmaster/scanners and their associated slave/advertisers always isaccording to schedules and BLE standards, as previously described.

If the above-mentioned dual mode capability is provided, the first [3-1]and second [3-2] master/scanners may selectively either (1) operate asdescribed above according to a non-continuous predetermined schedule asdescribed above, or (2) communicate aggregated data in a continuousmanner without waiting for scheduled times in accordance with thecontinuous classic standard Bluetooth mode of operation.

Operation with continuous communication between master/scanners has theadvantage of providing reduced “latency” (which is the amount of timerequired for data be propagated through the network) because there is nodelay waiting for scheduled communication times between master/scanners.A master/scanner that has just received a message can immediately sendit on through the network via other master/scanners. This may be veryadvantageous if increasing the speed of data through the network moreimportant than reducing its power consumption of the network. This alsomay be very advantageous if increasing the range (distance) of thenetwork is more important than reducing its power consumption.

The described embodiment of the invention uses standard BLE mechanismssuch as advertising and scanning to propagate a message with theintended recipient's MAC (media access control) address. A message isinitially advertised or “flooded” through the network. After the“shortest” wireless route between the initiating slave/advertiser andthe receiving master/scanner is determined by a series of master/slaveconnection requests propagating from the message recipient to themessage initiator, then subsequent messages between them use directedadvertisements only to nodes (master/scanners) along the preferred routedetermined by analyzing and culling previously established routes.Repeater nodes (i.e., master/scanners) in the described BLE network mustadvertise or scan continuously when a message is to be propagated inorder to minimize the amount of time a recipient node or master/scannerwould spend scanning or advertising during communication.

The described embodiment of the invention is interoperable with existingBLE enabled mobile phones/tablets and enables the propagation ofmessages between mobile wireless devices and sensors without requiringeither hardware changes or firmware changes to existing BLE enabledmobiles/tablets. Note that only firmware in a radio or transceiver hasto be changed or updated in order to enable use of the describedembodiment of the invention. The firmware update can be part of astandard update of the mobile phone/tablet operating system, in whichthe aforementioned behavior of the BLE functionality is implemented. Thedescribed embodiment of the invention provides a method for using a BLEnetwork wherein advertisements by a slave/advertiser are used totransmit data and connection requests between the master/scanner and anassociated slave/advertiser and are used for periodic phasesynchronization and acknowledgement of the transmitted data.Slave/advertisers are periodically resynchronized to account for driftbetween internal clock signal signals in master/scanners and associatedslave/advertisers. RSSI information and the number of hops required foraggregated data to be propagated to a master/scanner or slave/advertisernode are utilized to establish and then “cull” wireless connections toestablish the preferred route between a message-initiating node and amessage-receiving node, without use of routing information or routingtables.

Furthermore, the described embodiment of the invention provides a BLEnetwork that requires substantially less power than prior BLE networks,is substantially less expensive, is easier to use, and is interoperablewith newer mobile phones.

While the invention has been described with reference to severalparticular embodiments thereof, those skilled in the art will be able tomake various modifications to the described embodiments of the inventionwithout departing from its true spirit and scope. It is intended thatall elements or steps which are insubstantially different from thoserecited in the claims but perform substantially the same functions,respectively, in substantially the same way to achieve the same resultas what is claimed are within the scope of the invention.

What is claimed is:
 1. A BLE (Bluetooth low energy) network comprising:a first piconet including a first master/scanner and a first group ofslave/advertisers for transmitting wireless advertisements and forestablishing wireless connections, respectively, with the firstmaster/scanner; wherein each slave/advertiser in the first group canonly establish a wireless connection with the first master/scanner;circuitry in the first master/scanner for wireless scanning to detect anadvertisement transmitted by a first slave/advertiser of the firstgroup, transmitting a connection request in response to the detecting tothe first slave/advertiser, and transmitting a schedule for subsequentadvertisements after an initial advertisement by the firstslave/advertiser to complete synchronization of the first master/scannerwith the first slave/advertiser; circuitry in the first slave/advertiserfor transmitting the initial advertisement, receiving and accepting aresulting connection request, and establishing an association with thefirst master/scanner, after which the first slave/advertiser goes tosleep in a reduced-power mode, waking up and transmitting subsequentadvertisements according to the schedule, and accepting resultingconnection requests from the first master/scanner when data is availableto be advertised, transmitting the available data to the firstmaster/scanner, and going back to sleep; circuitry in the firstmaster/scanner for transmitting an advertisement containing aggregateddata received from the first slave/advertiser to a secondmaster/scanner; a second piconet including the second master/scanner anda second group of low-power slave/advertisers for transmitting wirelessadvertisements and establishing wireless connections, respectively, withthe second master/scanner, the second piconet also including circuitryin the second master/scanner for wireless scanning to detect anadvertisement transmitted by a second slave/advertiser of the secondgroup and transmitting a connection request in response to thedetecting, and transmitting a schedule for subsequent advertisementsafter an initial advertisement by the second slave/advertiser; andcircuitry in the second slave/advertiser for transmitting the initialadvertisement, receiving and accepting a resulting connection request,establishing an association with the second master/scanner, and thencausing the second slave/advertiser to go to sleep in a low-power mode,waking up and transmitting subsequent advertisements only according tothe schedule, and accepting resulting connection requests from thesecond master/scanner when data is available to be advertised,transmitting the available data to the first master/scanner, and causingthe second slave/advertiser to go back to sleep; and circuitry in thesecond master/scanner for transmitting an advertisement containingaggregated data received from the first slave/advertiser to a thirdmaster/scanner.
 2. The BLE low energy network of claim 1 includingcircuitry in the first and second master/scanners for selectively either(a) communicating the aggregated data to the second master/scanneraccording to a non-continuous predetermined schedule in a BLE mode ofoperation, or (b) communicating the aggregated data from the firstslave/advertiser to the second master/scanner in a manner that iscontinuous and not according to a schedule.
 3. The BLE low energynetwork of claim 1 wherein the first master/scanner operates to cull aconnection with another master/scanner based on RSSI levels ofadvertisements received from the other master/scanner and the number ofhops between master/scanners along a particular route required foraggregated data from the first slave/advertiser to reach a destinationof the aggregated data.
 4. The BLE low energy network of claim 3 whereinwhen both the first master/scanner and the second master/scanner aretransmitting the same particular set of aggregated data to the thirdmaster/scanner and data loading of the second master/scanner is greaterthan data loading of the first master/scanner, then the culling includesoperating the third master/scanner to cause the second master/scanner tostop sending the particular set of aggregated data to the thirdmaster/scanner.
 5. The BLE low energy network of claim 1 wherein theaggregated data is accumulated in a data packet that includesinformation identifying a slave/scanner that first advertised theaggregated data and also identifying an upstream destination of theaggregated data.
 6. The BLE low energy network of claim 1 includingrepeating scanning and advertising operations of master/scanners alongan established route including the first and second master/scannersuntil the aggregated data reaches a predetermined destination.
 7. Amethod of operating a BLE (Bluetooth low energy) network, the methodcomprising: providing a first piconet including a first master/scannerand a first group of slave/advertisers for transmitting wirelessadvertisements and for establishing wireless connections, respectively,with the first master/scanner; wherein each slave/advertiser in thefirst group can only establish a wireless connection with the firstmaster/scanner; operating a first slave/advertiser of the first group totransmit an initial advertisement; operating the first master/scanner ina scanning mode to detect the initial advertisement and to transmit acorresponding connection request in response to the detecting to thefirst slave/advertiser; operating the first slave/advertiser to receiveand accept the corresponding connection request and establish anassociation with the first master/scanner; operating the firstmaster/scanner to transmit to the first slave/advertiser a schedule forsubsequent advertisements to synchronize the first master/scanner withthe first slave/advertiser, and causing the first slave/advertiser to goto sleep; operating the first slave/advertiser to wake up and transmitsubsequent advertisements according to the schedule, and operating thefirst master/scanner to simultaneously scan for the subsequentadvertisements according to the schedule and transmit connectionrequests corresponding to the subsequent advertisements, and operatingthe first slave/advertiser to accept corresponding connection requestsfrom the first master/scanner when the first slave/advertiser has dataavailable to be advertised; operating the first slave/advertiser toadvertise the available data to the first master/scanner, and operatingthe first master/scanner to aggregate the advertised available data;providing a second piconet including a second master/scanner and asecond group of low-power slave/advertisers for transmitting wirelessadvertisements and establishing wireless connections, respectively, withthe second master/scanner; operating the second master/scanner inwireless scanning to detect an advertisement transmitted by a secondslave/advertiser of the second group and transmitting a connectionrequest in response to the detecting, and transmitting a schedule forsubsequent advertisements after an initial advertisement by the secondslave/advertiser; operating the second slave/advertiser for transmittingthe initial advertisement, receiving and accepting a resultingconnection request, establishing an association with the secondmaster/scanner, and then causing the second slave/advertiser to go tosleep in a low-power mode, waking up and transmitting subsequentadvertisements only according to the schedule, and accepting resultingconnection requests from the second master/scanner when data isavailable to be advertised, transmitting the available data to the firstmaster/scanner, and causing the second slave/advertiser to go back tosleep; and operating the second master/scanner to transmit anadvertisement containing aggregated data received from the firstslave/advertiser to a third master/scanner.
 8. The method of claim 7including operating the first master/scanner to transmit connectionrequests only when the advertisements meet a predetermined RSSI(received signal strength indicator) requirement.
 9. The method of claim7 wherein the schedule requires a predetermined number of allowedadvertisements by the first slave/advertiser before it initiatesresynchronization of the first slave/advertiser with the firstmaster/scanner to compensate drift between internal clock signals of thefirst slave advertiser and the first master/scanner, respectively. 10.The method of claim 7 including operating the first master/scanner tocull a connection with another master/scanner based on RSSI levels ofadvertisements received from the other master/scanner and the number ofhops between master/scanners along a particular route required foraggregated data from the first slave/advertiser to reach a destinationof the aggregated data.
 11. The method of claim 10 wherein the cullingincludes operating the first master/scanner to command anothermaster/scanner having heavy data loading to stop sending redundant datato the first master/scanner.
 12. The method of claim 7 includingrepeating scanning and advertising operations of master/scanners alongan established route until the aggregated data reaches a predetermineddestination.